Electric thermostat.



C. L. NORWOOD.

ELECTRIC THERMOSTAT. APPLICAHON men MAY 2. 1911.

1,248,894. Patented Dec. 4,1917.

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CHARLES 'n 'u'onwoob, or PHILADELPHIA, PENNSYLVANIA.

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Specification of Letters Patent. a

Patented Dec. 4, 1917.

Application filed May 2, 1917. Serial No. 185,904.

To all whom it may concern: 1

Be it known that I, CHARLES L. Nonwooi), a citizen of the United States, residing at Philadelphia, in the county of Philadelphia and State of Pennsylvania, have invented certain new and useful Improvements in Electric Thermostats, of which the following is a specification. J

he ob ect of this invention is to supply a long-felt need in the maintenance of substantially constant temperature and ventilation within a building.

More specifically the invention provides a most efiicient thermostat for regulating the amount of heat supplied to a given room or compartment, as well as automatically adjusting means for modifying the excessive heat therein in warm weather.

The object of the invention is furthermore to provide means for shutting off the heat supply as the temperature rises above a certain predetermined point, and shortly above said point to make effective a cooling medium, such as a refrigerating means, or to simply turn on an electric fan.

And a further object is to provide an inclosure for the thermostat comprising the invention, which is both neat and attractive tothe eye, and acts to rotect the latter from the effect of dust, dlrt, or the like.

These and other objects of the invention, together with the details of the construction and operation thereof, are fully brought out in the accompanying drawings in which Figure 1 is an elevational view ofthe preferred form of the device as secured to the wall surface of a room; Fig. 2 is a central vertical section of the same; Fig. 3 is an enlarged detail view showing the means for formln the electrical connections of the circuits o the device; and Fig. 4 is a Wiring diagram of the electrical circuits employed in the device forming this embodiment of the invention.

Referring to the drawings, the preferred embodiment of the invention comprises a glass thermometer tube 1, having an enlarged reservoir 2 at one end, and partially filled with mercury 3, or other material capable of relatively great contraction and expansion upon being subjected to changes in cold and heat intensities.

Resting upon the upper end of the said mercury column is a pellet 4 of suitable in-,

su ating material, Supporting in turn a loosely fitting metallic cylinder 5, or short mercury column, which by virtue of the peculiar capillary characteristics of that metal will. remain separated from the lower col- .umn, without tending to'pass around the said pellet, the true shapes of the neighboring surfaces of the two columns being substantially as shown. j

The reservoir 2 of the tube is preferably supported" by resilient arms 6 partially embracing the same, while the upper portion of the tube is held in upright position by means of resilient fingers 7-, both of said arms and fingers being unitarily secured to the front wall of a casing 8, provided with slanting side walls 9, and a vertically extending slot 10.

Also secured to the inner side surface of the 'said casing is a bar 11 upon which are slidably mounted a pair of sleeves 12, having pins 13 which pass outwardly through the said slot 10, and are capped with pointers 14, which indicate their positions vertically by means of the graduations 15.

The wall of the room in, which the thermostat is located is provided behind the casing 8 with a yielding contact 16, which normally presses against a stud or contact member 17 sealed into the rear side of the tube 1. Also, each of the sleeves 12 is provided with a yielding contact member 18,

adapted to carry current to sealed-in studs or contact members 19 and 20 as the former slide over the latter successively;

With this construction, the two pointers are set at the respective temperatures at which the apparatus is desired to operate,

say for instance 75 and 70. Then, when the temperature forces the mercu column and the up er superimposed cylin er in accordance with the heat of 75 or more, electric current passes through the wire 22, cylinder 5, one of the studs 19, neighboring contact 18 and sleeve 12, wire 23, fan 24' (or refrigerating system) and return wire 25.

The temperature by this operation is in- 1 directly forced downward until the c linder 5 breaks the contact with the stu 19, and there remains between 70 and 75.

10a However, if it continues below the former I 7 temperature, contact is made between the.

said cylinder and one of the contacts 20,

thus com leting the circuit throu h the wire 22, cylin er 5, stud 20, neighborlng contact 18 and sleeve 12 wire 26 and heat-regulather, an upper and a lower series of coning valve 273 the like, and wire 28, which tacts sealed in said tube and adapted to be 20 eventually connects with the wire 25. in contact with said member as it is moved This invention'may also be used to re by said column upon a change in tempera- 5 late the temperatures of vulcanizers, which ture, a casing for said tube, means carried is believed to be between 250 and 300, as by said casing to support said tube, a rod. well as for breaking the charging current carried by said casing, and electrical con- 25 when in the operation of char 'ng storage tacts slidably carried by said rod and adaptor secondary batteries the same ecome daned to contact with the contacts of said series 1 gerously overheated. selectively upon predetermined changes in Having thus described my invention, temperature. what I claim and desire to protect by Let- In testimony whereof I have aflixed my 30 tel; Platent of the United S1tates is signature in presence of two witnesses.

t ermostatic circuit 0 oser comprisin 1 5 a mercur tube, a metallic member actuate CHARLES NORWOOD' directly y the mercury column, and-insu- W1tnesses: lated therefrom, a'contact sealed in-the said J. STUART FREEMAN,

tube and normally in contact with said mem- AMY B. Home. 

